video: fbdev: s3fb: suppress build warning

this patch fixes following build warning:
drivers/video/fbdev/s3fb.c: In function ‘s3_pci_probe’:
drivers/video/fbdev/s3fb.c:1185:23: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
  par->state.vgabase = (void __iomem *) vga_res.start;
                       ^
Signed-off-by: NLad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/fbdev/s3fb.c

@@ -1182,7 +1182,7 @@ static int s3_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
 
 	pcibios_bus_to_resource(dev->bus, &vga_res, &bus_reg);
 
-	par->state.vgabase = (void __iomem *) vga_res.start;
+	par->state.vgabase = (void __iomem *) (unsigned long) vga_res.start;
 
 	/* Unlock regs */
 	cr38 = vga_rcrt(par->state.vgabase, 0x38);